[1] Nanyang Technol Univ, Sch Phys & Math Sci, Div Phys & Appl Phys, Singapore 637371, Singapore
[2] Nanjing Univ Posts & Telecommun, Key Lab Organ Elect & Informat Displays, Nanjing 210046, Jiangsu, Peoples R China
[3] Nanjing Univ Posts & Telecommun, Inst Adv Mat, Nanjing 210046, Jiangsu, Peoples R China
[4] Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore
[5] Nanjing Univ Technol, Jiangsu Singapore Joint Res Ctr Organ Bioelect &, Nanjing 211816, Jiangsu, Peoples R China
[6] Nanjing Univ Technol, Inst Adv Mat, Nanjing 211816, Jiangsu, Peoples R China
[7] Huazhong Univ Sci & Technol, Sch Mat Sci & Engn, State Key Lab Mat Proc & Mould Technol, Wuhan 430074, Hubei, Peoples R China
[8] Natl Univ Singapore, Fac Sci, Dept Phys, Singapore 117542, Singapore